Gleb, 37, and Elena, 36, announced earlier this month they had decided to call it quits on their relationship after 14 years of marriage, with Elena accusing Gleb of "ongoing infidelity" and "multiple affairs" -- including "a recent inappropriate relationship" that broke her trust.
Gleb's fame and life in the spotlight "took a big toll on Elena, and it was hard for her to adjust," added the source.
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Meanwhile, Gleb reportedly "isn't bothered by the attention and is just trying to live his best life and move forward" after the separation from his wife, with whom he shares two daughters -- Olivia, 10, and Zlata, 3.
"His main focus is on his kids and trying to spend as much time with them as possible and also making time for himself," the source said.
"Gleb feels secure and fully supported by the cast throughout everything. Everyone knew this was coming for a long time. So, they aren't surprised and just have his back."
While the source called Elena "insecure," another Us insider recently suggested Gleb gave Elena every reason to feel jealous.
The insider said Gleb and Chrishell "had an attraction toward each other right at the beginning" of the Dancing with the Stars season and "definitely had a flirty relationship" while competing on the show.
Gleb and Chrishell's immediate connection reportedly led to the pair "texting a lot and hanging out outside of work."
"Chrishell and Gleb are still texting all the time and have been in contact about the public frenzy surrounding them," the insider elaborated, referring to Gleb's split from Elena.
Shortly after Elena and Gleb announced their split about a week ago, Chrishell denied playing any role in the breakup amid speculation she and Gleb had a secret fling or romance.
"I am so saddened about the news of Gleb and Elena's split. It is unfortunate that this has caused rumors to swirl about my personal life," Chrishell reportedly wrote on Instagram Stories at the time.
Alluding to her own divorce from actor Justin Hartley, Chrishell continued, "Having gone through a public split myself, I would not wish this on anyone. As you can imagine, the countless hours of training, and dance rehearsals has created a strong supportive friendship, but nothing more. I wish nothing but the best for both Gleb and Elena during this unfortunate time."
But Elena later told People, "After 14 years of marriage, and multiple affairs, I've decided enough is enough."
"Gleb and I have created a family and multiple businesses together. But apparently, it just wasn't enough to keep our marriage strong. Gleb's ongoing infidelity and a recent inappropriate relationship has created turmoil in our marriage and absolutely torn our family apart."
Elena continued, "No wife should ever stand by and watch while another woman gifts her husband expensive presents, lures him out to dinners and seduces him at every turn. Last night was the final straw, and I can no longer turn my head the other way."
But Gleb subsequently denied engaging in a relationship with another woman and cheating on his wife.
"While I will continue to respect the privacy of my family, I will not stand by and allow false accusations and Internet rumors go unaddressed," Gleb told People in a statement, before insisting he and Chrishell are nothing more than friends.
"My relationship with Chrishell was and remains strictly platonic," Gleb said.
"Our friendship during our season on DWTS was not the reason for our split. Elena and I have had longstanding issues in our marriage. This has been an ongoing situation between Elena and I paired with poor timing."
Gleb added, "It was my deepest hope to keep our private life just that: private. I am saddened and disappointed to see that Elena has chosen not to do the same."
Chrishell's representative also backed Gleb's claims by denying allegations she had any romantic involvement with the Russian pro dancer.
"Any insinuation or accusation that Chrishell is in any way involved in the dissolution of Gleb and Elena's marriage is 100 percent categorically false," Chrishell's representative told People in a statement.
"To be clear: Chrishell and Gleb are in no way, and have never been in any way, romantically involved."
Elena first broke the news of her split from Gleb on November 6 in her Instagram Stories.
"After 14 years of marriage with my deepest sadness our road is coming to an end," Elena wrote alongside a photo of Gleb and herself.
The blonde mother of two then posted a quote on her Instagram account that seemingly accused Gleb of being at fault for the demise of their marriage.
"I don't hate you, i'm just disappointed you turned into everything you said you'd never be," the quote read.
Not long after Elena went public with the breakup, Gleb posted his own message on Instagram and confirmed the breakup.
"It is with a heavy heart that I tell you my wife and I are parting ways after 14 years of marriage. We still intend to co-parent our wonderful children together who we love so dearly, and we will strive to continue to be the best parents that we can to them," Gleb wrote alongside a family photo with Elena and their children.
"We ask that you respect our family's need for privacy and healing during this time."
Gleb and Elena's failed marriage may come as a surprise to fans since they just celebrated their 14th wedding anniversary in July and everything seemed to be fine between the couple.
"Two souls but with a single thought, two hearts that beat as one. Happy 14th Anniversary my love," Gleb wrote on Instagram at the time.
And Elena -- who wed Gleb in 2006 -- had posted a video montage of her relationship with Gleb over the years in honor of their anniversary.
"14 years Together!" Elena captioned the video clip, along with three heart emojis. "Real Love stories never have endings @glebsavchenkoofficial now it's 4 of us #love #family #14anniversary."